In multimedia interface for which the needs has been sharply increased recently, under various user circumstances such as in public, office, home and the like, a high speed and large volume data transmission is desired. As one of multimedia interfaces which provide such high speed and large volume data transmission, a high speed wireless access network, a high speed radio access network or the like are getting the focus of public interest.
As an example of typical structure of such networks, a master-slave type network and a direct link type network are given. In the master-slave type network, by means of a central control via a communication terminal holding apparatus, a plurality of terminal apparatuses carry out communication with the communication terminal holding apparatus. On the other hand, in the direct link type network, by means of a central control via a communication terminal holding apparatus, which has the control right, in one or more communication terminal holding apparatuses, a plurality of terminal apparatuses and another communication terminal holding apparatus carry out each communication.
A master-slave type network shown in FIG. 1 comprises a communication terminal holding apparatus 11 having access point (AP) facility, which is equivalent to a base station apparatus in a mobile communication system, and MT device apparatus 12, 13 and 14 having mobile terminal (MT) facility respectively, which is equivalent to mobile station apparatus such as a portable telephone apparatus or the like. In the master-slave type network, the communication terminal holding apparatus 11 carries out a scheduling thereby communication resources such as time area and frequency or the like are assigned, and communication between the MT device apparatus is always carried out via the communication terminal holding apparatus 11.
A direct link type network shown in FIG. 2 comprises CC/WT device apparatuses 21 and 22 which have a central controller (CC) facility and a wireless terminal (WT) facility, and WT device apparatuses 23 and 24 which have a WT facility only, and communications are performed between the WT device apparatuses directly. In this case, the control right is transferred between the CC/WT device apparatuses 21 and 22, which have a CC facility respectively, and the apparatus having the control right carries out the scheduling.
Accompanying the expansion of application field of the network, are quest to put to use such a network that a master-slave type network and a direct link type network are integrated with each other. Now, such a network that has a communication terminal holding apparatus 31 provided with CC/WT/AP facilities, which is capable of including both of MT device apparatus of a master-slave type network and WT device apparatus of a direct link type network as shown in FIG. 3, will be considered.
To carry out a high speed and large volume data transmission by means of a multimedia radio communication system, it is essential to carry out scheduling effectively on a limited communication resources and various scheduling methods have been proposed. For example, a method is disclosed in a Japanese Unexamined Patent Application Publication No. 11-243578, in which, for a purpose of reducing the controlling load of a base station and making the buffer size smaller even when the number of terminal apparatuses is increased, terminal apparatuses are divided into groups when including the terminal apparatuses and assignment of communication resources is carried out in each group.
In a conventional communication terminal holding apparatus 31 also in a network shown in the foregoing FIG. 3, the scheduling is carried out so as to prevent any competition or collision of the communication resources from occurring when carrying out communications between a WT device apparatus and an MT device apparatus. Now, referring to a timing sheet in FIG. 4, an operation of scheduling in a conventional communication terminal holding apparatus 31 will be described while taking an example of a case where a communication request is made from the WT device apparatus 24 to the MT device apparatus 14. In FIG. 4, the description will be made as to the case where the communication resources are divided on the basis of time region.
First of all, the communication terminal holding apparatus 31 carries out a scheduling to assign communication resources Ta-b of a period of time from a to b, which is presently not used in a direct link type network, and makes a notice of control information 41, which instructs to transmit data by means of a communication resources Ta-b, to the WT device apparatus 24. Then, the WT device apparatus 24 transmits the data 42 by means of the communication resources Ta-b, and the communication terminal holding apparatus 31 receives the data.
Then, the communication terminal holding apparatus 31 carries out a scheduling to assign communication resources Tc-d of a period of time from c to d, which is presently not used in the master-slave type network, and makes a notice of control information 43, which instructs to receive the data by means of the communication resources Tc-d, to the MT device apparatus 14. Then, the communication terminal holding apparatus 31 transmits the data 42 by means of the communication resources Tc-d, and the MT device apparatus 14 receives the data.
As described above, the conventional communication terminal holding apparatus carries out the scheduling on each network to prevent any competition or collision of the communication resources from occurring, once the transmitted data is received from a transmitting side terminal apparatus by means of a certain communication resources by its own apparatus and transmits the data to a receiving side terminal apparatus by means of other communication resources.
However, in the scheduling method of the conventional communication terminal holding apparatus, when carrying out communications between the terminal apparatuses which are held in different networks respectively, since communication resources of different periods of time for transmission and for reception are assigned respectively, such a problem that a high speed and large volume data transmission is prevented from being realized resides in. For example, in a case of the foregoing FIG. 4, in order to transmit the data 42 from the WT device apparatus 24 to the MT device apparatus 14, two periods of communication resources Ta-b and communication resources Tc-d are required.